This patent application claims the benefit and priority of Chinese Patent Application No. 202211592393.0 filed with the China National Intellectual Property Administration on Dec. 13, 2022, the disclosure of which is incorporated by reference herein in its entirety as part of the present application.
The present disclosure relates to the technical field of mining engineering, and particularly to a rapid mining method for sandstone-type uranium resources in a uranium and coal superposed area.
Uranium resources are important strategic resources, and more than 90% of natural uranium production comes from sandstone-type uranium deposits. Most sandstone-type uranium deposits coexist with strategic mineral resources such as coal, petroleum, natural gas in the same basin, and superposition and symbiosis of uranium and coal is the most commonly phenomenon. A development strategy of “uranium before coal” is put forward in view of the superposition and symbiosis of uranium and coal. The mining strategy of “uranium before coal” points out a scientific mining sequence for collaborative development of uranium and coal resources in this area, and further puts forward higher requirements for development efficiency and technical level of uranium resources.
The design life of an in-situ leaching uranium mining mine in China is generally 15 years to 20 years, and the design service life of a single mining area is 6 years to 8 years. The most important factors affecting a mining speed of a mining area are a uranium concentration of a leaching solution, and pumping and injection flow. Excluding objective factors and factors of a mineral deposit itself, the uranium concentration of the leaching solution is related to mining engineering means, a formula and a concentration of a leaching agent, and the pumping and injection flow is related to a lowering depth of a submersible pump, a pumping drawdown and a injection pressure. Under the actual condition of a CO2+O2 in-situ leaching uranium mining process, it is difficult to achieve an 80% recovery rate in the mining area within 6 years. Especially in the middle and later stages of leaching, there are many problems such as a serious blockage of deposit, decrease in the pumping and injection flow, low uranium concentration of a leaching solution, a dead corner of leaching, and the like. The service life of the mining area is required to be extended to 8 years to 10 years, or even longer.
Taking a super-large sandstone uranium deposit in the Ordos basin where uranium and coal are superimposed as an example, according to the development scale and mining method of the largest single in-situ leaching mine in China, 30 years or even longer of service life of the mining area are required. Under the condition that uranium and coal resources are not superposed in space, it is advisable to exchange time for economic exploitation of sandstone-type uranium deposits. However, under the condition that many coal mines in the Ordos basin have been put into production or completed well construction, a water level of a sandstone uranium reservoir continues to decline due to drainage of nearby coal mines, and rescue development of uranium resources in this area is imminent. Moreover, under the development strategies of uranium and coal superposition and “uranium before coal”, it is necessary to speed up the development of uranium resources and provide development spaces and conditions for overlaid coal resources as soon as possible.
In order to solve the above problems, the present disclosure provides a rapid mining method for sandstone-type uranium resources in a uranium and coal superposed area from the aspects of a well type, a well spacing, a pumping and injection exchange mode during production operation, high-efficiency intensified leaching, high-intensity extraction, pressurized liquid injection, balance regulation and control, etc., so as to improve a recovery speed of the sandstone-type uranium resources, and shorten the service life of the in-situ leaching mining area.
In order to realize the above objective, the present disclosure provides a technical solution as follows.
A rapid mining method for sandstone-type uranium resources in a uranium and coal superposed area, which includes:
Preferably, a distance between the pumping well and the injection well is 20 m to 27 m.
Preferably, the determining a length and a position of a filter located on the in-situ leaching mining area through a digital well construction technology specifically includes:
Preferably, the carrying out pumping/injection centralized filtration by the filter on the in-situ leaching mining area specifically includes:
Preferably, the carrying out intensified leaching through a strong oxidation reaction and a strong complexation reaction in the production stage specifically includes:
Preferably, in the advanced oxidation and strong oxidation reactions, oxygen is added into an in-situ leaching process through a micro-nano oxygen injection technology; and
Preferably, the carrying out high-intensity injection through a pressurized injection and uniform injection regulation and control mode in the production stage specifically includes:
Preferably, the changing a layout of the high-density adjustable well pattern in the production stage specifically includes:
According to the specific embodiments provided in the present disclosure, the present disclosure discloses technical effects as follows.
The present disclosure relates to a rapid mining method for sandstone-type uranium resources in a uranium and coal superposed area, which is used for a situation in which the sandstone-type uranium deposits are required to be rapidly mined under the conditions of uranium-coal superposition or other backgrounds. The present disclosure includes rapid mining measures and methods in a design stage and a production stage of the sandstone-type uranium deposit mining area. Specifically, through combined means of a high-density adjustable well pattern and digital well construction technology, pumping/injection centralized filtration, intensified leaching, high-intensity extraction, pressurized injection and uniform injection regulation and control, and well pattern regulation and control in a production stage, rapid mining purposes of a small leaching dead angle, a large leaching coverage rate, a high uranium concentration of a leaching solution, a large pumping and injection flow and a good permeability of an ore-bearing aquifer are realized. Therefore, service life of the in-situ leaching mining area can be effectively shortened, and the recovery of sandstone-type uranium resources can be accelerated.
In order to describe technical solutions in embodiments of the present disclosure or in the prior art more clearly, accompanying drawings required to be used in the embodiments will be briefly described below. Apparently, the accompanying drawings in the following description show merely some embodiments of the present disclosure, and those of ordinary skill in the art can derive other accompanying drawings from these accompanying drawings without creative efforts.
Technical solutions of embodiments of the present disclosure will be clearly and completely described below in combination with accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are merely some embodiments rather than all embodiments of the present disclosure. All other embodiments derived by those of ordinary skill in the art on the basis of embodiments of the present disclosure without creative efforts shall all fall within the scope of protection of the present disclosure.
In order to make the above objectives, features and advantages of the present disclosure clearer and more comprehensible, the present disclosure will be further described in detail below in combination with accompanying drawings and specific embodiments.
An embodiment of the present disclosure provides a rapid mining method for sandstone-type uranium resources in a uranium and coal superposed area. According to an embodiment of the present disclosure, through combined means of a high-density adjustable well pattern and digital well construction technology, pumping/injection centralized filtration, intensified leaching, high-intensity extraction, pressurized injection, uniform liquid injection regulation and control, and well pattern regulation and control in a production period, on the basis of precise mining of a sandstone uranium ore, rapid mining is realized with a small leaching dead angle, great pumping and injection intensity and a good permeability of a deposit are realized, thus service life of a mining area is shortened, and recovery of sandstone-type uranium resources in a uranium and coal superposed area is accelerated.
The technical solution in an embodiment of the present disclosure includes rapid mining measures and methods in development, design and production stages of sandstone uranium ore in a uranium and coal superposed area, which are described as follows in combination with
In step 100, a high-density adjustable well pattern is arranged in an in-situ leaching mining area. The in-situ leaching mining area is a uranium and coal superposed area, the high-density adjustable well pattern is in a form of a five-spot well pattern, a well diameter of an injection well located at an edge of the high-density adjustable well pattern is a first well diameter, a well diameter of a injection well and a well diameter of a pumping well located at non-edge of the high-density adjustable well pattern are both second well diameters, and the first well diameter is less than the second well diameter.
Different from the existing seven-spot well pattern form and five-spot well pattern form of in-situ leaching uranium mining, in the present disclosure, a well diameter is optimized, and a five-spot well pattern form with part of the injection wells and part of the pumping wells having the same well diameter is used. Under the condition of saving well drilling cost as much as possible, the adjustment of well pattern pumping and injection functions in the middle and later stages of production in the in-situ leaching mining area is satisfied, which facilitates exchange of well types during the production process.
Specifically, the high-density adjustable well pattern provided in an embodiment of the present disclosure includes multiple squares, as shown in an area a in
In the high-density adjustable well pattern, a distance between the pumping well and the injection well, that is, a distance between the pumping hole and injection hole, is 20 m to 27 m, which is different from a distance between the pumping hole and the injection hole of 27 m to 40 m used in a conventional in-situ leaching mining area.
In step 200, a length and a position of a filter located on the in-situ leaching mining area are determined through a digital well construction technology, which is specifically as follows.
In step 300, mining operations are carried out to obtain sandstone-type uranium resources in the uranium and coal superposed area at a production stage.
The mining operations include the following steps S1 and S2.
Before the in-situ leaching mining area is put into production, water pumping and injection circulation is carried out on an ore-bearing aquifer by the filter to realize the pre-dredging of the ore-bearing aquifer, where circulation time is 3 days to 5 days.
After the in-situ leaching mining area is put into production, pumping/injection centralized filtration is carried out by a filter loaded with a reagent of “limestone and quartz sand” with a particle size of 2 mm to 5 mm. Specifically, a main pipe of a leaching raffinate is connected to the filter, and the leaching raffinate is filtered by the filter, added with a leaching agent, and then injected into the ore-bearing aquifer through the injection well.
The filter is a common tower tube, which is similar to a resin adsorption tower for hydrometallurgy in the in-situ leaching uranium mining. In the embodiment, the filter is a ceramic container with high pressure resistance and corrosion resistance or a ferruginous container lined with PO, which is equipped with a liquid inlet pipe, an air inlet pipe, a liquid discharge pipe, an exhaust pipe and an automatic backflushing valve, etc., so as to facilitate loading, unloading and automatic flushing of limestone and quartz sand. The tower is loaded with solid particles of “limestone and quartz sand” with a particle size of 2 mm to 5 mm, and the limestone and quartz sand particles are proportioned according to a ratio of 2:1 to 1:1.
The filter filled with limestone and quartz sand is porous medium material, which reduces a flow rate of a solution and realizes settlement of fine particles. Moreover, surfaces of the limestone and the quartz sand can absorb colloids and suspended matters, so as to purify the solution. This is a low-cost method for intercepting impurities to purify the solution, which can filter out 90% or above of fine silts and suspended colloids in a pumped/injected liquid. Obviously, centralized filtration of a pumped solution (equivalent to a leaching solution) is carried out, so as to reduce adverse effects of silts and colloids on a uranium hydrometallurgical adsorption system.
In step 500: high-intensity extraction is carried out through a high-lift and large-flow submersible pump operation mode in the production stage.
A production process of in-situ leaching uranium mining belongs to group well operation, the pumping well and the injection well are arranged according to certain rules (five-spot type, seven-spot type or determinant rules, etc.), the injection of the injection well may be regarded as a constant head recharge boundary of the pumping well. A calculation formula of a water level drawdown and a water pumping flow can refer to:
where Q denotes a water overflow rate of well, with a unit of m3/d; K denotes a permeability coefficient of the aquifer, with a unit of m/d; denotes a length of the filter, with a unit of m; M denotes a thickness of the aquifer, with a unit of m; S denotes a drawdown of water level in the well, with a unit of m; r denotes a radius of the well, with a unit of m; and R denotes a influence radius of water pumping, with a unit of m.
For a certain pumping well, the permeability coefficient of the ore-bearing layer, the thickness of the ore-bearing layer, the length of the filter, the radius of the well and the influence radius of water pumping (an interval between the pumping well and the injection well) in the above formula are all determined, and the water pumping flow of the pumping well may be improved only by increasing the drawdown of water level. For a sandstone uranium ore with relatively poor permeability (permeability coefficient K≤0.5 m/d), a means of adopting a high-lift and large-flow submersible pump for operation and enlarging a dewatering funnel to increase a liquid pumping flow of the drilling well has been verified by practice. See Table 1 for details.
Under a drilling well pattern layout condition in the step 100, during the well pattern production scheduling in the production stage, in the early and middle stage of production (from production to an end of the 3rd year) in the mining area, an “I-type” five-spot type is used, as shown in a in
Under an ideal homogeneous stratum condition, a seepage field between the pumping well and the injection well is in a shape of a regular “spindle”, as shown in
In middle and later stage of leaching in the mining area, there are at least two advantages in exchanging the functions of the pumping well and the injection well according to the “II-type” five-spot rule.
Compared with the prior art, the beneficial effects of the present disclosure are as follows.
In view of rapid development of uranium resources in uranium and coal superposed sandstone, in the design stage of sandstone uranium mining, the scientificity of well spacing determination and filter layout is improved through a high-density adjustable well pattern and digital well construction technology, and well pattern density for the purpose of rapid mining of uranium resources and a preferred filter layout scheme for the purpose of reducing vertical dilution are determined.
In the production stage of the in-situ leaching mining area, through pumping/injection centralized filtration, the blockage of the ore-bearing aquifer by fine particles and colloids is reduced, and good permeability of the ore-bearing aquifer is kept. The oxidation and complexation conditions of sandstone-type uranium resource leaching are simultaneously strengthened, and the concentration of the key leaching agent is increased to accelerate the chemical reaction process. High-intensity extraction is carried out, so as to carry out large-drawdown water pumping by a high-lift and large-flow submersible pump, and to increase the liquid pumping flow of the leaching unit, which is the most direct way to improve a mining speed. Pressurized injection is carried out, the hydraulic gradient between the injection well and the pumping well is increased, the seepage velocity of the leaching solution is increased, and moreover, uniform liquid injection regulation and control are carried out, so as to reduce dilution and a non-uniform degree of leaching in different directions of the same leaching unit as much as possible. In the early and middle stage of production in the mining area, the “I-type” five-spot type is used, and in the later stage of production, the “II-type” five-spot type is used, so as to reduce the leaching dead angle under the pumping and injection mode of the fixed well pattern, and improve the recovery rate of uranium resources.
Through an optimization design of the mining area and a series of strengthening measures in the production stage, uranium resources in the uranium and coal superposed area can be rapidly mined.
Embodiments in the specification are described in a progressive manner, each embodiment focuses on the difference from other embodiments, and the same and similar parts between the embodiments may refer to each other.
In this specification, specific examples are used to explain principles and implementations of the present disclosure. The description of the foregoing embodiments is merely intended to help understand the method in the present disclosure and its core ideas. Moreover, various modifications can be made by those of ordinary skill in the art in terms of specific implementations and the scope of application in accordance with the ideas of the present disclosure. In conclusion, the content of the specification shall not be construed as limitations to the present disclosure.
Number | Date | Country | Kind |
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202211592393.0 | Dec 2022 | CN | national |